Drosophila, like many poikilothermal animals, is able to acclimate to extreme environmental temperatures. The purpose of this research is to determine the metabolic changes that occur during temperature acclimation in Drosophila and to identify some of the genetic and metabolic factors that influence the capacity of the animal to acclimate. Our specific goals for the year are 1) to establish the types of control that regulate tissue levels of the oxidative NADP-enzymes during temperature and dietary acclimation; 2) to compare metabolic changes in cold-resistant and cold-sensitive individuals upon cold exposure; 3) to examine D. melanogaster populations where pentose shunt deficient and proficient individuals are in competition under different temperature and nutritional conditions; and 4) to ascertain whether concurrent drug exposure interpheres with temperature acclimation in Drosophila.